The charmonium state \(\psi (3770)\) , lying about 40 MeV above the open charm threshold,
is expected to decay dominantly into the OZI allowed final state, \(D\bar{D}\) , together
with a small fraction of hadronic and radiative transitions into final states
with a lower mass charmonium state. However, the total cross section
\(\sigma (e^+e^-\rightarrow \psi (3770))\)  measured by counting the total number of inclusive
hadronic events is not saturated by \(D\bar{D}\)  measured by counting the number
of charged and neutral \(D\bar{D}\)  pairs [1]}, [2]}.
The hadronic transitions and the radiative transitions of the \(\psi (3770)\) 
can be calculated reliably in the quark models [3]}
and have been measured precisely in experiments [4]}.
This indicates that noticeable charmless decays of the \(\psi (3770)\) , i.e.,
\(\psi (3770)\rightarrow \text{\it light hadrons}\) , may exist.
On the other hand, people did elaborate studies to search for exclusive
charmless decays and failed to find any mode with a large branching
fraction [5]}, [6]}.
